Attrition mill



Sept. 3, 1935. D, B, MCLAUGHLIN 2,013,246

ATTRITION MILL Filed Jan. 24, 1929 Patented Sept. 3, 1935 .NETE

STTE

PTEN'' FFICE 9 Claims.

Itis common practice to mount the grinding heads of attrition mills upon the ends of a pair of axially aligned shafts and to feed the grain orotherV material to be ground through a central opening in one of the heads. In operation the rapidly rotating heads create suction in the feedpassageway, the ground material being delivered at' the outer periphery of the heads. Gravel, small pieces of rock and other objectionable foreign matter are frequently mixed with the grain to be ground and are sometimes delivered into the mill. It is important to exclude as much of this foreign matter as possible both for the protection of the grinding plates and to improve the product.

In my improved mill I increase the rate of grinding and make a more uniform product by providing means for properly distributing the grain in the feed passages vand for automatically separating the heavier foreign matter from the grain in the mill.V

Further, in order to save wear on the bearings and retain the proper parallelism of the grinding heads, it will be evident that the runners or shafts -driving the grinding heads should be supported at points as closely adjacent to the grinding faces as possible. One of my objects is to provide an arrangement whereby the weight of the grinding heads is supported more closely adjacent to the grin-ding faces than has heretofore beenpossible. Y

My invention will be best understood by reference to the accompanying drawing in which Figure 1 is a side elevation of my improved attrition mill; Fig. 2 is a central longitudinal section through the mill proper; Fig. 3 is a transverse. section .taken on the line 3-3 of Fig. 1 and Fig. Llis a detail front elevation of the feed pedestaland cone.

The several parts of the machine are secured to a suitable bed 4 and motors 5 and 6 are arranged todrive the head and tail shafts 'i' and 8, respectively. These shafts i and 8 are mountedin axial alignment and are revoluble in a series of` bearings supported in standards 9, I@ and II and ina fourth bearing, hereinafter particularly described. The ends of the shafts I and 8 extend in close proximity, one to the other, Within a housing I2 between the motors 5 and 5 and within this housing grinding heads I3 and I4 are respectively mounted on said shafts. To supportthe overhanging-end of the shaft I an anti-friction bearing I5 is placed in the hollow interior of a substantially conical projection or deflector I6 formed in a base I'I supporting a hopper I 8 for the material to be ground. The otherwise conical deflector I5 has a series of annular shoulders or rings Ita upon its surface to direct the material toward the grin-ding heads and around the deflector. A conduit I9 for conducting the material to be ground to the grinding heads extends around the exterior of the conical projection I6 and communicates with the Working faces of the grinding plates 20 through openings 2| in the head I3. A hub I3I mi, of the head I3 is fixed on the extremity of the shaft i and the material to be ground passes through the openings 2l between spokes I3b of the head. Beneath the conical projection I6 is a receptacle 22 for the heavier foreign matter me and an opening 23 in the base I 'I allows access to the receptacle 22 upon the removal of aplate 23a (Figs. 1 and 3). Air is admitted to the conduit I9 through a screen-covered opening 24 beneath the hopper I8. A suitable feed roll 25 is 20, arranged to be driven by a belt (not shown) run4` ning on a drive pulley 26 on the shaft l and on a driven pulley 21 on the spindle of the roll 25.

To support the shaft 8 at a point closely adjacent to the grinding head lli, an anti-friction bearing 28 is mounted in the standard Ill. Access to the bearings I5 and 28 is facilitated by providing removable plates 29 around the shafts I and 8 and enclosingthe bearing recesses respectively.

303 Operation.

The motors 5 and 6 are operated to drive the shafts 'l and 8 in opposite directions so` that the grinding plates 29 are rotated at high speed in opposite directions. Grain or other material to be ground may be fed continuously from the hopper IB by the operation of the feed roll 25. The rapidlyrotating heads I 3 and I 4 cause the material to be directed outward by centrifugal 40 force so that the material is delivered through an opening 3i! in the bed and suction is created in the feed conduit I9. Air is drawn in through the opening 25 and as it approaches the grinding head I3 it is given swirling or rotary motion 45.. about the conical surface of the member` I6. The material to be ground is thus continuously delivered to the grinding surfaces and distributedV uniformly to the'fseveral segments ofthe plates 2l The heavier particles of foreign matter drop 5o i from the hopper upon the deflector I6 -and Vthe spokes lh assisted by the swirling draft of air direct such particles outward and backward into the receptacle 22 Where they lodge beneath the conical surface. The receptacle 22 may be 55 periodically emptied through the opening 23 which is normally closed by the plate 23a. The draft of air in the feed passage does not draw the heavier particles between the spokes 23h, but such particles are allowed to fall into the receptacle 22 past the lateral sides of the member I5.

Thus substantially all of the heavier particles of foreign matter, including the gravel which is apt to damage the grinding plates, is prevented from reaching the grinding surfaces. It will be now evident that the conical projection it serves the purposes of properly distributing the material in the feed passage, of directing Y the foreign matter into the trap receptacle 22 and of affording a support for the bearing l5 located close to the grinding head i3.

The annular shoulders or rings lGa are particularly useful in effecting a force feed of roughage, such as pieces of corn cob, which have atendency to work back and escape from the feed draft carrying the iner or lighter particles.

I-Iaving described my invention what I claim as new and desire to protect by Letters Patent is:

1. In a grinding mill, a shaft, a grinding head mounted on said shaft and having a feed opening therethrough, means for supplying the material to be Vground, a feed conduit connecting said supply means with said opening, a substantially conical member projecting into said conduit around said shaft to direct said material toward said opening and a receptacle disposed adjacent to the base of said member to collect the heavier foreign'matter.

2. In a grinding mill, a horizontal shaft, a grinding head mounted on said shaft and having a feed opening therethrough, a hopper for material to be ground mounted above said shaft, a feed conduit connecting said hopper with said opening, a substantially conical member projecting into said conduit beneath said hopper and extending around said shaft to direct said material toward said opening and a recep-tacle disposed beneath said member to collect the heavier foreign matter. k 3. In a grinding mill, a substantially horizontal shaft, a grinding head mounted on said shaft and having spokes between which material to be ground is fed, a hopper for said material mounted above said shaft, a feed conduit connecting said hopper with said head, a substantially conical deflector extending transversely in said conduit and around said shaft toward said head to distribute said material between said spokes, a substantially annular portion of said conduit being provided around said deflector adjacent to said head and said deflector having a bearing chamber therein an-d a bearing for supporting said shaft adjacent to said head mounted in said chamber.

4. In an attrition mill, a shaft, a grinding head mounted on said shaft and having a feed opening therethrough, grinding means associated with said head, means for supplying material to be ground, a feed conduit connecting said supply means with said opening, a substantially conical member projecting transversely in said conduit and extending around said shaft to direct said material toward said opening;l said grinding means and head being arrange-d to create a swirling draft of air in said conduit and around said member to draw the lighter particles of material into said opening and a receptacle disposed adja-V cent to the base of said member to collect the heavier particles of foreign matter separated from said material.

5. In an attrition mill, a horizontal shaft, aV

grinding head mounted on said shaft and having a feed opening therethrough, grinding means associated with said head, means above said shaft for supplying material to be ground, a feed conduit connecting said supply means with said opening, a substantially conical member projecting transversely in said conduit directly beneath said supply means and extending around said shaft to direct said material toward said opening, said grinding means and head being arranged to create a swirling draft of air in said conduit and around said member to draw the lighter particles of material into said opening and a receptacle disposed beneath said member to collect the heavier particles of foreign matter in saidY ing draft of air in said conduit and around said member to draw the lighter particles of material` into said opening, a bearing supported by said member adjacent to said head and a receptacle disposed adjacent to the base of said member to collect the heavier particles of foreign matter separated from said material.

7. In a grinding mill, a shaft, a grinding head mounted on said shaft and having a feed opening therethrough, a feed conduit communicating with said opening, a substantially conical member projecting into said conduit to direct material -to be ground toward said head and substantially annular projections on said member to direct said material around said member.

8. A mill of the character described comprising a horizontal rotary shaft, grinding means mounted thereon, an inclined feeder shoe proper and an enclosing conical shell therefor extending substantially parallel with the feeder shoe, both having their lower ends conical laterally and enclosing said shaft and having said ends disposed directly adjacent to said grinding means, anda bearing for said shaft located within the conical end of the shoe proper and adjacent to said grinding means, substantially as described.

9. Armill of the character described comprising a casing, a horizontal rotary shaft mounted therein, a grinding disc having feed openings therein and mounted on the end of said shaft in said casing, a laterallyv conical feeder shoe disposed directly adjacent to said grinding disc and consisting of a shoe proper and an enclosing coni- 

